JP2005327743A - Spark plug with resistor, resistor composition for spark plug, and manufacturing method of spark plug with resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spark plug with a resistor in which a stable loaded life characteristic is obtained even when a high load is applied, and furthermore in which prevention performance of the electric wave noise is hardly reduced even at high temperatures. <P>SOLUTION: In the spark plug 100, since a composition of the resistor composing the resistor 15 contains particles of ceramics with semiconductor nature, the spark plug has a superior load life characteristic. Furthermore, deterioration of electric wave noise prevention performance caused by the high temperatures can be suppressed effectively by setting (α2-α1)/α1≥-0.30 by assuming that a value of a resistance between a terminal fitting 13 and the center electrode 3 at 20°C is α1, and similarly the value at 150°C is α2. The composition of the resistor body is constituted so as to contain the particles of ceramics with semiconductor nature in which a temperature coefficient of the electrical resistance value shows a positive value or a comparatively small negative value of absolute value (for example TiO2 particles having rutile type crystal structure, titanates or zirconate or the like of an alkaline-earth metal element, and titanium suboxides), or to contain metal titanium. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a spark plug used for an internal combustion engine, and more particularly to a spark plug incorporating a resistor for preventing generation of radio noise.

  Conventionally, as a spark plug as described above, a terminal fitting is inserted and fixed from one end side of the through hole formed in the axial direction of the insulator, and the center electrode is also inserted from the other end side. A structure having a structure in which a resistor is disposed between the terminal fitting and the center electrode in the through hole while being fixed is known. For example, as disclosed in JP-A-61-104580, JP-A-61-253786, or JP-A-2-126584, this resistor is used for glass powder and / or insulating ceramic powder. A mixture of shaped carbon (for example, carbon black) and then sintered by hot pressing or the like is used.

  Here, in recent years, internal combustion engines such as automobile engines tend to have higher output, and the power supply capacity is also increasing to improve ignitability. In addition, with the miniaturization of the internal combustion engine, a spark plug with a resistor is required to be small and have high performance. And when a high load acts on such a spark plug with a resistor, particularly a small spark plug with a small diameter of the resistor, carbon imparting conductivity to the resistor burns out, and the resistance value increases. There is a problem that stable load life characteristics cannot be obtained.

  An object of the present invention is to provide a resistor-containing spark plug that can obtain stable load life characteristics even when a high load is applied, a method for manufacturing the same, and a resistor composition for use therein.

Means and actions / effects for solving the problems

  The spark plug containing a resistor according to the present invention has the following common structure. That is, with respect to the through hole formed in the axial direction of the insulator, the terminal metal fitting is fixed to one end side thereof, and the center electrode is similarly fixed to the other end side, and the terminal is disposed in the through hole. Between the metal fitting and the center electrode, a resistor composed of a resistor composition mainly composed of a conductive material, glass particles, and ceramic particles other than glass is disposed. In the first structure of the resistor-containing spark plug of the present invention, the resistor composition contains semiconducting ceramic particles as ceramic particles, and a resistance is provided between the terminal fitting and the center electrode. (Α2−α1) /α1≧−0.30, where α1 is a value at 20 ° C. and α2 is a value at 150 ° C. measured by energizing through the body. To do.

  As an attempt to improve the load life characteristics of the spark plug, a proposal for stabilizing the load life of a resistor by mixing TiO2 particles, which is a semiconductor oxide, in the resistor is disclosed in, for example, Japanese Patent Laid-Open No. 58-102480. JP-A-58-102481, JP-A-58-189917, JP-A-59-17201, JP-A-59-17202, JP-A-60-150601, JP-A-60-150602, And Japanese Patent Publication No. 5-52641. However, when the output of the internal combustion engine increases, the temperature of the spark plug attached to the internal combustion engine rises, and the temperature of the resistor incorporated therein is also heated to a high temperature of about 100 to 300 ° C., for example. There is. In such a state, there is a defect that the electric resistance value of the semiconductive TiO 2, and consequently the electric specific resistance of the resistor, is reduced, and the radio wave noise prevention performance is impaired.

  Therefore, in the first configuration of the present invention, in the spark plug in which the semiconductor ceramic particles are blended in the resistor, the electrical resistance measured by energizing the resistor between the terminal fitting and the center electrode. By setting (α2−α1) /α1≧−0.30, where α1 is the value at 20 ° C. and α2 is the value at 150 ° C., sufficient radio wave noise prevention performance can be obtained even at high temperatures. When (α2−α1) / α1 <−0.30, noise prevention performance at high temperature may be insufficient. More preferably, it is good to adjust in the range of (α2−α1) /α1≧−0.27.

  Next, the resistor composition has, as semiconductive ceramic particles, an average particle diameter of a particle image obtained when the cross-sectional structure is observed (hereinafter, simply referred to as an average particle diameter in this specification) of 0.5. While containing TiO2 particle | grains used as -20micrometer in 0.5-20 weight%, at least one part of the TiO2 particle | grain can have a rutile type crystal structure. Note that in this specification, all metal oxides are represented by a composition formula having a stoichiometric composition, but in actuality, a metal oxide may have a non-stoichiometric composition due to oxygen deficiency.

  According to this configuration, by including TiO2 particles in the range of 0.5 to 20% by weight in the resistor composition, good load life characteristics can be ensured even under high load conditions, and further in the resistor composition. By adjusting the average particle size of the TiO2 particles to be blended in the range of 0.5 to 20 μm and having at least a part thereof have a rutile-type crystal structure, high-temperature deterioration of the radio noise prevention performance due to the resistor is effective. Can be suppressed.

  For example, in the case of a resistor containing TiO2 particles and a nonmetallic conductive material such as carbon particles, the conductive path is determined by contact between the nonmetallic conductive materials, between the nonmetallic conductive material and the TiO2 particles, or between the TiO2 particles. It is formed. And it is thought that the electrical resistance value of a resistor is represented by the sum of the specific resistance (bulk resistance) of these particles and the contact resistance between the particles.

  Here, as a result of intensive studies by the present inventors, it has been found that the temperature dependence of the electrical resistance of the resistor as described above is mainly governed by the temperature change of the specific resistance of each particle. On the other hand, three types of TiO 2 are known as the atmospheric phase crystal structure: tetragonal rutile, tetragonal anatase, and orthorhombic brookite. Of these, the industrially important ones are the rutile type and the anatase type, but the above-described configuration of the present invention is that the rutile type of these two types of TiO2 is more specific than the anatase type. It was completed by paying attention to the fact that the temperature change of the film becomes smaller.

  When the content of TiO2 particles in the resistor composition is less than 0.5% by weight, the load life characteristics of the resistor are insufficient. On the other hand, if it exceeds 20% by weight, the noise prevention performance tends to deteriorate at high temperatures. The content of TiO2 particles in the resistor composition is desirably adjusted in the range of 2 to 20 wt%, more desirably 3 to 15 wt%.

  In general, TiO2 tends to stabilize the anatase crystal structure as the particle size decreases. And when the average particle diameter of TiO2 particle | grains will be less than 0.5 micrometer, the noise prevention performance by a resistor will become easy to deteriorate at high temperature. That is, the temperature characteristic of noise prevention performance is deteriorated. This is because the relative content of the anatase type phase is increased by making the contained TiO2 particles fine, the relative content of the rutile type phase is conversely insufficient, and the temperature characteristics of the noise prevention performance become insufficient. It is thought that. Another problem is that when the average particle size of the TiO2 particles is less than 0.5 μm, the bulk density of the TiO2 raw material powder increases, so that the density of the resistor obtained by firing is insufficient and noise prevention performance or load life is increased. This leads to the loss of properties. On the other hand, when the average particle diameter of the TiO2 particles exceeds 20 μm, the raw material powder particles of the resistor, such as a glass powder and a ceramic powder other than TiO2, which will be described later, including the TiO2 powder, are difficult to rearrange at the time of firing. Leads to a lack of density. The average particle diameter of the TiO2 particles in the resistor composition is more preferably adjusted in the range of 2 to 8 [mu] m.

  Next, it is desirable that 20% by weight or more of the TiO2 particles in the resistor composition have a rutile crystal structure (rutile type phase). In this case, the remainder of the TiO 2 particles can be composed of an anatase type crystal structure (anatase type phase). When the content ratio of the rutile phase in the total amount of TiO2 is less than 20% by weight, the temperature characteristics of noise prevention performance may be insufficient. The content ratio of the rutile phase is more preferably 30% by weight or more. On the other hand, the content ratio of the rutile type phase is preferably adjusted within a range of 80% by weight or less. Since the rutile type phase is generally coarser than the anatase type phase, when the content ratio exceeds 80% by weight, the resistor is formed mainly of TiO2 and a metal phase or non-metallic conductive material described later. In some cases, the thickness of the conductive path forming portion becomes uneven, and stable load life characteristics cannot be obtained. The content ratio of the rutile phase is more preferably 70% by weight or less.

  Further, the TiO2 particles in the resistor composition, when focusing on the particle size distribution, the content ratio of the TiO2 particles belonging to the particle size range 0.05 to 0.5 [mu] m is 20 to 80 wt%, the particle size range The content ratio of TiO 2 particles belonging to 2 to 8 μm is preferably 80 to 20% by weight in order to ensure stable load life characteristics and temperature characteristics of noise prevention performance. That is, most of the TiO2 particles belonging to the particle size range of 2 to 8 [mu] m are mainly composed of the rutile type phase, and the content ratio is set to 20% by weight or more to achieve good temperature characteristics in noise prevention performance. Can do. Further, the content ratio of the TiO2 particles belonging to the particle size range of 2 to 8 [mu] m is set to 80% by weight or less, and the content ratio of the TiO2 particles belonging to the particle size range of 0.05 to 0.5 [mu] m is adjusted within the above range, thereby making the resistor The thickness of the conductive path forming portion can be made uniform, and stable load life characteristics can be obtained. The content ratio of TiO2 particles belonging to the particle size range 0.05 to 0.5 μm is more preferably 30 to 70% by weight, and the content ratio of TiO2 particles belonging to the particle size range 2 to 8 μm is more desirable. Is preferably 70 to 30% by weight.

  Next, the resistor composition is composed of at least one of semiconducting metal titanate complex oxide and semiconducting zirconate complex oxide (hereinafter collectively referred to as both) as semiconductive ceramic particles. Is referred to as a specific composite oxide) in the range of 0.5 to 20% by weight.

  This configuration focuses on the fact that the temperature change of the specific resistance is small in the metal titanate complex oxide and the metal zirconate complex oxide compared to TiO2 that has been conventionally used as semiconductor ceramic particles. It has been completed. And by including the above-mentioned specific complex oxide in the range of 0.5 to 20% by weight in the resistor composition, good load life characteristics can be secured even under high load conditions, and noise prevention performance by the resistor Can be effectively suppressed.

  When the content of the specific composite oxide in the resistor composition is less than 0.5% by weight, the load life characteristic of the resistor becomes insufficient. On the other hand, if it exceeds 20% by weight, the noise prevention performance tends to deteriorate at high temperatures. The content of the specific composite oxide in the resistor composition is preferably adjusted in the range of 2 to 20% by weight, more preferably 3 to 15% by weight.

  As specific composite oxides as described above, alkaline earth metal element titanates or alkaline earth metal element zirconates have good semiconductor properties and a small temperature change in resistivity. It can be particularly preferably used in the invention.

  Such titanates or zirconates of alkaline earth metal elements include magnesium titanate (compositional formula: MgTiO 3, but may have a non-stoichiometric composition due to oxygen deficiency; the same applies hereinafter), zirconate Magnesium (composition formula: MgZrO3), calcium titanate (composition formula: CaTiO3), calcium zirconate (composition formula: CaZrO3), strontium titanate (composition formula: SrTiO3), strontium zirconate (composition formula: SrZrO3), titanate Examples include barium (composition formula: BaTiO3) and barium zirconate (composition formula: BaZrO3). In the present invention, one selected from these may be used alone, or two or more may be used in combination.

  The average particle size of the particles of the specific composite oxide in the resistor composition is preferably adjusted in the range of 0.5 μm to 20 μm. When the average particle size is less than 0.5 μm, the bulk density of the raw material powder of the specific composite oxide increases, and thus the resistance of the resistor obtained by firing is insufficient and the noise prevention performance or load life characteristics are impaired. There is. On the other hand, when the average particle size of the specific composite oxide exceeds 20 μm, the raw material powder particles of the resistor, including the specific composite oxide powder, such as a glass powder to be described later and a ceramic powder other than the specific composite oxide, are regenerated during firing. It becomes difficult to arrange, and the density of the resistors may be insufficient as well. The average particle size of the specific composite oxide in the resistor composition is more desirably adjusted in the range of 2 to 8 μm.

  Now, in the above configuration, among the ceramic particles contained in the resistor composition, the remaining amount excluding TiO2 particles or specific composite oxide particles (hereinafter referred to as auxiliary ceramic particles) is 2 to 32. It is good to be weight%. When the content of the auxiliary ceramic particles is out of the above range, the load life characteristics of the spark plug may be impaired. The content of the auxiliary ceramic particles is desirably adjusted in the range of 3 to 20% by weight. The auxiliary ceramic particles can be composed mainly of, for example, one or more of ZrO2, ZrSiO4, Al2O3, MgO, Al-Mg spinel and mullite.

  The resistor composition includes 2 to 90% by weight of glass, 2.5 to 52% by weight of ceramic particles (including TiO2 particles or specific composite oxide particles), and 0.1 to 5% by weight of a carbon component. It can comprise as what contains. Such a resistor composition includes, for example, 2 to 90% by weight of glass powder, 2.5 to 52% by weight of ceramic particles, and 0.1 to 5% by weight of a nonmetallic conductive material (for example, carbon black). By mixing 0.1 to 5% by weight of an organic binder (for example, PVA, etc.) and an appropriate amount of metal powder (which becomes a metal phase) as necessary to obtain a raw material powder, this is heated and molded. Can be obtained.

  Specifically, 3 to 20% by weight of glass particles having a particle size of less than 150 μm (hereinafter referred to as fine glass), and 60 to 90% by weight of glass particles belonging to a particle size range of 150 to 800 μm (hereinafter referred to as coarse glass). Metal powder mainly composed of 0.5 to 20% by weight of TiO2 particles or specific composite oxide particles, 2 to 32% by weight of auxiliary ceramic particles, and one or more of Al, Mg, Ti, Zr and Zn It can be produced by blending 0.05 to 0.5% by weight (being a metal phase) and 0.5 to 5.0% by weight of non-metallic conductive material powder and hot pressing.

  FIG. 4 schematically shows the structure of the resistor composition thus obtained. That is, at least a part of the fine glass is melted and solidified to form a bonded glass phase, in which a metal phase and non-metallic conductive material particles (hereinafter collectively referred to as conductive material powder) are dispersed to form a conductive path. It becomes a forming part. The conductive path forming portion forms a so-called block structure surrounding block glass particles derived from coarse glass. In this case, at least a part of the bonded glass phase forms a continuous part from the end part on the terminal fitting side to the end part on the center electrode side, and the continuous part is an electrical connection between the particles of the conductive material powder. The conductive path of the resistor is formed on the basis of such contact. And this continuous part, ie, a conductive path, is detoured everywhere by the interposition of block particles, the effective length becomes long, and a good effect of preventing generation of radio noise is achieved.

  The fine glass serves to fill a gap formed between particles of the coarse glass powder by melting at least part of it during hot pressing. However, if the particle size exceeds 150 μm, the melting is insufficient and voids are easily generated in the conductive path, leading to the deterioration of the load life characteristics of the plug. The particle size of the fine glass powder is desirably set within a range of 100 μm or less. On the other hand, when the particle size of the coarse glass is less than 150 μm, the particles are easily softened or melted at the time of heating and molding, and the above-mentioned block structure is damaged, and a good radio noise generation preventing effect is not achieved. On the other hand, if the particle size exceeds 800 μm, voids are likely to remain between the glass particles, leading to a deterioration in the load life characteristics of the plug.

  Moreover, when the weight of the fine glass is less than 3% by weight or the weight of the coarse glass exceeds 90% by weight, the glass hardly melts during hot pressing, and a large amount of voids are formed between the glass particles, The load life characteristics of the plug are impaired. On the other hand, if the weight of the fine glass exceeds 30% by weight or the weight of the coarse glass becomes less than 60% by weight, the content ratio of the block particles decreases, and the formation of the block structure becomes insufficient, resulting in good radio noise. Generation prevention effect is not achieved. The weight of the fine glass is desirably set in the range of 3 to 12% by weight. The weight of the coarse glass is desirably set in the range of 70 to 85% by weight.

  If the blending amount of the metal phase or non-metallic conductive material is out of the upper limit of the above range, the radio wave noise prevention effect may be insufficient. On the other hand, if the value falls outside the lower limit, the load life characteristics may be impaired. The blending amount of the metal phase is desirably adjusted in the range of 0.1 to 0.3% by weight, and the content of the nonmetallic conductive material is desirably adjusted in the range of 0.5 to 3.0% by weight. It is good to do.

  From the viewpoint of the structure, the resistor composition is preferably configured as follows. That is, the resistor composition comprises 50 to 90% by volume of block glass particles made of glass particles belonging to a particle size range of 150 to 800 μm, a conductive material, ceramic particles, and the conductive material and ceramic particles. It contains a bonded glass phase that is bonded to each other in a dispersed state to fill the space between the block glass particles, and includes 10 to 50% by volume of a conductive path forming portion that forms a conductive path in the resistor.

  When the content ratio of the block glass particles is less than 50% by volume, or the content ratio of the conductive path forming part in the resistance composition exceeds 50% by volume, the content ratio of the block particles decreases, and the block structure is formed. It becomes insufficient, and a good effect of preventing generation of radio noise is not achieved. Conversely, if the content of the block glass particles exceeds 90% by volume, or the content ratio of the conductive path forming part in the resistance composition is less than 10% by volume, a large amount of voids are formed between the glass particles, The load life characteristics of the plug are impaired. The content of the block glass particles is more desirably adjusted in the range of 20 to 40% by volume.

  In addition, as shown in FIG. 8, the particle size of the block glass particles is two parallel lines so as to be in contact with the outer shape line of the particle observed on the cross section of the resistor and not to cross the inside of the particle. A and B are defined as the maximum value d of the distance between the parallel lines A and B when various positions are drawn while changing the positional relationship with the particles (note that the particle diameter of the TiO2 particle image is also described above) the same). The volume content of the block glass particles can be calculated by dividing the total area of the block glass particles observed on the resistor cross section by the visual field area.

  The conductive material included in the conductive path forming portion includes, for example, a metal phase mainly composed of one or more of Al, Mg, Ti, Zr and Zn, and a non-metallic conductive material. Can do.

  In addition, the conductive path forming part includes 7.5 to 50% by weight of the bonded glass phase, 0.1 to 3.0% by weight of the metal phase, and a nonmetallic conductive material in the weight content ratio in the conductive path forming part. In the range of 1.2 to 12.5% by weight and ceramic particles in the range of 5 to 80% by weight (of which TiO2 particles or specific composite oxide particles are 5 to 50% by weight).

  When the content ratio of the bonded glass phase in the conductive path forming portion is less than 7.5% by weight, the glass hardly melts during hot pressing, and a large amount of voids are formed between the glass particles, so that the load life characteristic of the plug is improved. Damaged. On the other hand, if it exceeds 50% by weight, the relative proportion of the metallic phase or non-metallic conductive material is reduced, leading to the deterioration of the load life characteristics. Moreover, if the content ratio of the metal phase or the non-metallic conductive material particles in the conductive path forming portion is out of the upper limit value in the above range, the radio noise prevention effect may be insufficient. On the other hand, if it deviates from the lower limit value, the load life characteristics may be impaired.

Furthermore, when the content ratio of the TiO 2 particles or the specific composite oxide particles in the conductive path forming portion is less than 5% by weight, the load life characteristic of the resistor becomes insufficient. On the other hand, if it exceeds 50% by weight, the noise prevention performance tends to deteriorate at high temperatures. In this case, the volume ratio of the TiO2 particles or the specific composite oxide particles in the conductive path forming portion is adjusted in the range of 5 to 50% by volume, preferably 20 to 40% by volume for the same reason. This volume content VR is, for example, the area ratio of ceramic particles observed in the cross-sectional structure of the resistor composition, S0, and identified by X-ray diffraction or the like. The content volume of the composite oxide particles is V1, and the content volume of the auxiliary ceramic particles is V2.
VR = {S0 × V1 / (V1 + V2)} × 100 (volume%) (1)
Can be calculated.

  The non-metallic conductive material can be constituted mainly of one or more of amorphous particles (carbon black), graphite, SiC, TiC, WC and ZrC. In this case, the resistor composition contains a carbon component based on the non-metallic conductive material, and the carbon component mainly exists in the conductive path forming portion. For example, when carbon black is used, at least a part of the carbon component is contained in the conductive path forming portion in the form of carbon black particles.

  The content of carbon in the resistor composition is preferably adjusted in the range of 0.5 to 5.0% by weight. When the carbon content is less than 0.5% by weight, the load life characteristics of the spark plug may be impaired. On the other hand, if the carbon content exceeds 5.0% by weight, the effect of preventing radio noise may be insufficient. The carbon content is more desirably adjusted in the range of 0.5 to 3.0% by weight. Note that the nonmetallic conductive material may contain a carbon component derived from an organic binder for powder molding.

  In the present invention, the material of the glass particles is, for example, B2O3-SiO2 type, BaO-B2O3 type, SiO2-B2O3-CaO-BaO type, SiO2-ZnO-B2O3 type, SiO2-B2O3-Li2O type, and SiO2-B2O3. What contains 1 or more types of each -Li2O-BaO type | system | group glass powder can be used. In this case, by using a softening temperature of 800 ° C. or lower, the fluidity of the glass at the time of melting is enhanced, and the bonded glass phase is sufficiently spread between the block particles so that the gaps are not easily formed. . As a result, the load life characteristics of the plug are improved. Here, the softening temperature of the glass means a temperature at which the viscosity becomes 4.5 × 10 7 poise. When the softening temperature is less than 300 ° C., the heat resistance of the resistor is impaired. Therefore, it is preferable to use glass having a softening temperature of 300 to 800 ° C., more preferably 600 to 800 ° C. Note that the material of the glass may be different between coarse glass (or block glass particles) and fine glass (or bonded glass phase).

  Here, for the softening temperature of the glass, the content of the oxidizable element component such as B, Si, Ca, Ba, Li, etc. in the glass particles of the resistor is analyzed to calculate the oxide-converted composition. A glass sample is prepared by blending and dissolving the oxide raw materials of each oxidizable element component so as to be almost equal to the composition, and then rapidly cooling to make a glass sample, and the softening point of the glass sample can be estimated from the softening point of the glass sample.

  Further, it is desirable to use a glass particle having a difference between the softening temperature of fine glass and the softening temperature of coarse glass of 100 ° C. or less. That is, it is desirable that | TF−TC | ≦ 100 ° C. when the softening temperatures of fine glass and coarse glass are TF and TC, respectively. In this case, either TF> TC or TF <TC may be used. The reason will be described below.

  First, fine glass and coarse glass have the property that the former is more likely to be deformed during hot pressing than the latter even if the viscosity is the same. In the case of TF> TC, if | TF−TC | ≦ 100 ° C., even if the softening temperature of the fine glass is somewhat higher than that of the coarse glass, the fine glass is sufficiently deformed by the pressure during hot pressing, Since the gaps between the glass grains are filled, the load life characteristics of the plug are maintained well. However, if | TF−TC |> 100 ° C., the deformation of the fine glass becomes insufficient, and a gap may be formed between the coarse glass, resulting in a decrease in load life characteristics. On the other hand, when TF <TC, the fine glass is more easily deformed and gaps are not easily formed. However, when | TF−TC |> 100 ° C., the viscosity of the glass becomes too low, and the conductivity is reduced. There are cases where voids due to the foaming of the fine glass are likely to occur in the path forming portion, resulting in a decrease in load life characteristics. Therefore, | TF−TC | is desirably 100 ° C. or less, and | TF−TC | is desirably 50 ° C. or less.

  Next, the resistor composition is composed of a metal phase mainly composed of Ti as a conductive material (hereinafter referred to as Ti-based metal phase) and titanium suboxide represented by a composition formula TinO2n-1 as semiconductive ceramic particles. It is also possible to configure it as containing at least one of particles. Here, titanium suboxide refers to titanium oxide having a lower oxygen content than titanium dioxide, and can also be expressed as a composition formula TiOx (x <2).

  Conventionally, anatase-type TiO2 blended in a resistor composition is semiconducting and has a property that its electrical resistance value decreases as the temperature rises (that is, has a negative temperature coefficient). In this case, since the rate of change of the electrical resistance value accompanying the temperature rise is relatively large, the electrical resistance value greatly decreases at high temperatures. If the amount is excessively increased, the radio noise prevention performance at high temperatures is impaired. There are drawbacks. On the other hand, the titanium suboxide has the same semiconductivity, but the rate of change of the electrical resistance value with increasing temperature is smaller than that of titanium dioxide, so that the decrease in the electrical resistance value of the resistor at high temperature is suppressed, which is good even at high temperature. Secures radio noise prevention performance. In addition, Ti-based metals have an electrical resistance value that increases conversely as the temperature rises (that is, has a positive temperature coefficient), and therefore have the same effect as titanium suboxide with respect to resistance reduction suppression at high temperatures. . Further, the Ti-based metal phase and titanium suboxide particles in the resistor act as a load life stabilizing material, and the effect of improving the load life characteristics of the resistor is also achieved. Note that either the Ti-based metal phase or the titanium suboxide particles may be contained alone in the resistor composition, or both may be mixed.

  In this case, the total content of the Ti-based metal phase and / or titanium suboxide particles in the resistor composition is adjusted in the range of 0.5 to 10% by weight, so that the above effect becomes more remarkable. can do. If the total content is less than 0.5% by weight, the effect of suppressing an increase in resistance value at high temperatures may be insufficient. Moreover, when this total content exceeds 10 weight%, the excessive increase in the electrical specific resistance of a resistor composition may be caused.

  The average particle diameter of the Ti metal phase and / or titanium suboxide particles is preferably adjusted in the range of 5 to 100 μm. When the average particle size is less than 5 μm, the oxidation reaction of the Ti-based metal phase and / or titanium suboxide particles is likely to proceed during the production of resistors, and the effect of suppressing the increase in resistance value at high temperatures is insufficient. There is a case. On the other hand, if the average particle size exceeds 100 μm, the electrical resistivity of the resistor composition may be excessively increased. The average particle size is desirably adjusted in the range of 10 to 30 μm.

In the present invention, the titanium suboxide particles are mainly composed of at least one of TiO (crystal system: cubic system), Ti2O3 (crystal system: hexagonal system), and Ti3O5 (crystal system: monoclinic system). can do. Of these, Ti3
O5 is particularly suitable for the present invention because it is stable against humidity, atmosphere, and the like. The compositional formulas of the various titanium suboxides exemplified here are all expressed in stoichiometric ratios, but may have a non-stoichiometric composition due to oxygen deficiency.

  The ceramic particles other than titanium suboxide can be composed mainly of one or more of ZrO2, ZrSiO4, Al2O3, MgO, Al-Mg spinel and mullite.

  The resistor composition contains 2 to 60% by weight of glass, 2 to 65% by weight of ceramic particles (including titanium suboxide particles), and 0.1 to 7% by weight of a carbon component. Can be configured. Such a resistor composition includes 2 to 60% by weight of glass particles, 2 to 65% by weight of ceramic particles (including titanium suboxide particles), and 0.1 to 5% by weight of non-metallic conductive material ( For example, carbon black), 0.1 to 5% by weight of an organic binder (for example, PVA) and an appropriate amount of metal powder (which becomes a metal phase) are mixed to form a raw material powder, which is molded. -It can be obtained by heating.

Further, the mixing ratio of the raw material powder of the resistor composition is preferably as follows.
Fine glass: 0.5 to 20% by weight;
Coarse glass: 50-90% by weight;
Ti metal particles and / or titanium suboxide particles: 0.5 to 10% by weight;
Auxiliary ceramic particles: 0.1 to 6% by weight;
0.5 to 7.0% by weight of non-metallic conductive material particles.

  Moreover, when it sees from a viewpoint of a structure | tissue, it is good to contain 50-90 volume% of the above-mentioned block glass particle, and 10-50 volume% of a conductive path formation part similarly. The conductive material particles contained in the conductive path forming portion contain metal phase particles mainly composed of one or more of Al, Mg, Ti, Zr and Zn, and non-metallic conductive material particles. Can be.

  Further, the volume ratio of the Ti-based metal phase or titanium suboxide particles in the conductive path forming portion is preferably adjusted in the range of 5 to 50% by volume, desirably 20 to 40% by volume. When the volume ratio is less than 5% by volume, the load life characteristic of the resistor becomes insufficient. Moreover, when it exceeds 50 volume%, noise prevention performance will deteriorate easily at high temperature.

  Also in this case, as the nonmetallic conductive material particles, amorphous carbon (carbon black), graphite, SiC, TiC, WC, ZrC, and the like can be used. The carbon content in the resistor composition is preferably adjusted in the range of 0.5 to 7.0% by weight as described above. When the carbon content is less than 0.5% by weight, the load life characteristics of the spark plug may be impaired. On the other hand, if the carbon content exceeds 7.0% by weight, the effect of preventing radio noise may be insufficient. The carbon content is more desirably adjusted in the range of 2.0 to 5.0% by weight.

  Next, a second configuration of the resistor-containing spark plug of the present invention is characterized in that the resistor composition contains at least one of TiC particles and TiN particles as a nonmetallic conductive material.

  When the spark plug resistor is exposed to severe conditions such as high voltage and high temperature, oxidation proceeds with the passage of time of use. Here, as the non-metallic conductive material, the above-mentioned carbon black is often used conventionally, but when the carbon black is oxidized, it changes to CO or CO2 and disappears. May soar. However, by using at least one of the TiC particles or TiN particles in place of the carbon black or together with the carbon black, the following advantages are produced. That is, TiC and TiN do not disappear even when oxidized, and become semiconductive TiO2 (or titanium suboxide), so that a rapid increase in resistance can be suppressed. The particle size of TiC or TiN is generally as large as several μm (10 to 100 times that of carbon black particles), and it takes a long time to be completely oxidized. Therefore, a spark plug excellent in durability with little change in the diameter of the resistor can be obtained.

  In this case, the total content of TiC particles and / or TiN particles in the resistor composition is preferably set in the range of 1 to 10% by weight. If the total content is less than 1% by weight, the absolute amount of the conductive material may be insufficient and the initial resistance value may be increased. In addition, since the conductive path becomes thin, the load per unit area increases, and the durability may deteriorate. On the other hand, if the total content exceeds 10% by weight, the initial resistance value becomes too low, and the desired radio noise prevention performance may not be obtained.

  Further, the TiC particles and / or TiN particles in the resistor composition have an average particle size of 5 μm or less when the cross-sectional structure is observed, so that TiC particles per resistor unit volume and / or Or since the specific surface area of TiN particle | grains can fully be ensured, the time-dependent change of resistance value decreases, and durability of a resistor can be improved. Further, it becomes easy to adjust the resistance value of the resistor to a desired target value.

  Furthermore, the oxygen content in the TiC particles and / or TiN particles is preferably 3.0% by weight or less. In other words, TiC particles and / or TiN particles used as starting materials for the resistor composition may be those having an oxygen content of 3.0% by weight or less. If the oxygen content exceeds 3.0% by weight, the oxygen concentration in the surface layer of the particles increases, the contact resistance between the particles increases, and the durability of the resistor may deteriorate.

  The resistor composition can be configured to contain 20 to 80% by weight of glass and 2 to 60% by weight of ceramic particles. Such a resistor composition comprises 1 to 10 wt% TiC particles and / or TiN particles, 20 to 80 wt% glass powder, 2 to 60 wt% ceramic powder, and 0.5 to 5 wt%. % Organic binder (such as PVA) and a suitable amount of metal powder (which becomes a metal phase) or non-metallic conductive material other than TiC particles and / or TiN particles (such as carbon black) as necessary. It can be obtained by heating and molding the powder.

In this case, the mixing ratio of the raw material powder of the resistor composition is preferably as follows.
Fine glass: 0.5 to 20% by weight;
Coarse glass: 50-90% by weight;
Ceramic particles: 2 to 60% by weight;
Non-metallic conductive material particles (including TiC particles and / or TiN particles): 1 to 10.0% by weight.

  Moreover, when it sees from a viewpoint of a structure | tissue, it is good to contain 50-90 volume% of the above-mentioned block glass particle, and 10-50 volume% of a conductive path formation part similarly. The conductive material included in the conductive path forming portion contains, for example, a metal phase mainly composed of one or more of Al, Mg, Ti, Zr and Zn, and the non-metallic conductive material. It can be.

  Further, the volume ratio of the TiC particles and / or TiN particles in the conductive path forming portion is adjusted in the range of 5 to 50% by volume, desirably 20 to 40% by volume. When the volume ratio is less than 5% by volume, the load life characteristic of the resistor becomes insufficient. Moreover, when it exceeds 50 volume%, noise prevention performance will deteriorate easily at high temperature.

  In addition to TiC particles and / or TiN particles, for example, when a carbon-based conductive material such as carbon black or graphite is blended, the content excluding those contained in the TiC particles among the carbon components in the resistor composition Is preferably 7.0% by weight or less. If this content exceeds 7.0% by weight, the effect of preventing radio noise may be insufficient.

  Next, the third configuration of the spark plug of the present invention and the manufacturing method thereof are as follows: the resistor composition constituting the resistor is mainly glass particles, ceramic particles other than glass, and an average particle size of 20 nm. It is produced using raw material powder composed of carbon black particles of ˜80 nm.

  Carbon black is interposed between other raw material powder (glass, ceramic) particles in the resistor, and primary particles of carbon black are linked one-dimensionally to form a chain structure (structure). Are two-dimensionally coupled to form a conductive network of resistors.

  Here, when the raw material powder of the resistor is prepared by wet mixing using an aqueous solvent, the carbon black has poor dispersibility due to factors such as low wettability with water having a large specific gravity, especially when the particle size is small. If the structure is long, its uniform distribution becomes difficult. As a result, carbon black is unevenly distributed in the resistor composition. When glass sealing is performed using this resistor composition, the resistance value of the obtained resistor varies and the conductive path becomes local. There is a problem that the current density is concentrated and the load life characteristics of the spark plug become unstable. On the other hand, when the particle size of the carbon black becomes too large, or when the structure is short, the conductivity decreases, so the amount of carbon black needs to be increased. However, carbon black has a much smaller particle size than other raw material powders such as glass and ceramics. Therefore, if the amount is too large, the bulk density of the raw material powder increases, and bridging of the powder particles occurs. Since it becomes easy, compressibility will be impaired. As a result, there is a problem that the density of the obtained resistor does not increase, the amount of defects such as voids increases, and the load life characteristics of the spark plug become unstable.

  As a result of intensive studies in view of this viewpoint, the present inventors have found that the average particle size of the carbon black to be used is 20 nm to 80 nm, so that there is little variation in the resistance value of the obtained resistor, and this is used. It was found that the load life characteristics of the spark plug can be stabilized.

  The reason why the average particle size of carbon black is limited to 20 to 80 nm is as follows. First, by setting the average particle size to 20 nm or more, the distribution of carbon black in the resistor composition can be made uniform, variation in resistance value of the resistor is suppressed, and current paths are dispersed. Therefore, current density concentration is less likely to occur. On the other hand, when the average particle size is 80 nm or less, good conductivity can be obtained even if the blending amount of carbon black is reduced. As a result, the amount of fine carbon black used can be reduced compared to other raw material powders such as glass powder and ceramic powder, and the bulk density of the raw material powder of the resistor composition can be increased. The density of the resistor to be obtained is improved, and as a result, a resistor having few defects and a stable load life can be obtained. The average particle size of carbon black is desirably 30 to 50 nm.

  In this case, carbon black powder having a DBP (dibutyl phthalate) amount of 60 to 120 ml absorbed by 100 g of carbon black as defined in Japanese Industrial Standard K6221, Method A of 6.1.2 is used. Is good. Since the DBP absorption amount increases as the structure length in the carbon black powder increases, it can be used as an index reflecting the structure length (hereinafter, measured in this specification). The absorption amount of DBP is referred to as “structure length”).

  When the length of the carbon black structure is 120 ml / 100 g or less, the structure can be uniformly distributed in the resistor, current paths are dispersed, and current density does not easily concentrate. On the other hand, when the structure length is 60 ml / 100 g or less, good conductivity can be obtained with a small amount of carbon black, the amount of carbon black used is reduced, and the raw material powder of the resistor composition is reduced. Bulk density is increased. Thereby, the density of the finally obtained resistor is improved, and a resistor having few defects and a stable load life can be obtained. The length of the structure is desirably 80 to 100 ml / 100 g.

  In this case, the raw material powder of the resistor composition is 20 to 90 wt% glass powder, 20 to 50 wt% ceramic powder, 5 to 30 wt% carbon black powder, and 0.05 to 5 wt%. It is preferable to use an organic binder. If the blending amount of the glass powder is less than 20% by weight, it may not be possible to ensure good sealing properties. On the other hand, if this exceeds 90% by weight, the load life characteristics may be insufficient. The blending amount of the glass powder is desirably 70 to 80% by weight. On the other hand, if the ceramic powder is less than 20% by weight or the carbon black powder is less than 5% by weight, the conductive path may become too thin and the load life may be reduced. On the other hand, if the ceramic powder exceeds 50% by weight or the carbon black exceeds 30% by weight, the effect of preventing radio noise is reduced. Desirably, the ceramic powder is 20 to 30% by weight, and the carbon black is 5 to 10% by weight.

  In each resistor composition of the present invention, the value of electrical specific resistance at 20 ° C. is preferably adjusted in the range of 50 to 2000 Ω · cm. When the value of the electrical specific resistance is less than 50 Ω · cm, noise prevention performance may be insufficient. Moreover, when it exceeds 2000 Ω · cm, the load life characteristics may be insufficient. The value of the electrical specific resistance is more preferably adjusted in the range of 100 to 1200 Ω · cm.

  The fourth structure of the resistor-containing spark plug of the present invention is that the resistor composition is TiO2 having an average particle diameter of 0.5 to 20 [mu] m when the cross-sectional structure is observed as ceramic particles. It is mainly composed of a resistor composition containing particles in a range of 0.5 to 20% by weight, and at least a part of TiO2 particles in the resistor composition has a rutile-type crystal structure. To do.

  Further, the fifth configuration of the resistor-containing spark plug according to the present invention is that the resistor composition is a ceramic particle having a semiconducting metal titanate-based complex oxide and a semiconducting zirconate-metal salt based complex oxide. It is characterized by containing at least one of (specific composite oxide) in the range of 0.5 to 20% by weight.

  Further, the sixth configuration is such that the resistor composition has a metal phase mainly composed of Ti as a conductive material (hereinafter referred to as Ti-based metal phase) and ceramic particles represented by the composition formula TinO2n-1. It consists of a resistor composition containing at least one of titanium oxide particles.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, some embodiments of the present invention will be described with reference to the drawings.
A spark plug 100 as an example of the present invention shown in FIG. 1 and FIG. 2 is formed at a distal end of a tubular metal shell 1, an insulator 2 fitted inside the metal shell 1 so that a tip portion 21 protrudes. One end is joined to the center electrode 3 and the metal shell 1 provided inside the insulator 2 in a state where the ignition portion 31 is protruded, and the other end is bent back to the side. Includes a ground electrode 4 disposed so as to face the tip of the center electrode 3. Further, the ground electrode 4 is formed with an ignition part 32 that faces the ignition part 31, and a gap between the ignition part 31 and the opposing ignition part 32 is a spark discharge gap g.

  The metal shell 1 is formed in a cylindrical shape by a metal such as low carbon steel, and constitutes a housing of the spark plug 100, and a screw portion 7 for attaching the plug 100 to an engine block (not shown) on its outer peripheral surface. Is formed. Note that 1e is a tool engaging portion that engages a tool such as a spanner or a wrench when the metal shell 1 is attached to the engine block, and has a hexagonal axial cross-sectional shape. In addition, the outer diameter of the screw part 7 is 10-18 mm (for example, 10 mm, 12 mm, 14 mm, 18 mm).

  The insulator 2 has a through-hole 6 for fitting the center electrode 3 along its own axial direction inside, and is mainly composed of alumina, for example, and has an Al component weight of 85 to 98 in terms of Al2O3. It is comprised as an alumina type ceramic sintered compact containing weight% (desirably 90 to 98 weight%).

  Next, a through hole 6 is formed in the axial direction of the insulator 2, and the terminal fitting 13 is inserted and fixed from one end side, and the center electrode 3 is also inserted and fixed from the other end side. Has been. The terminal fitting 13 is made of low carbon steel or the like, and a Ni plating layer (layer thickness, for example, 5 μm) for corrosion prevention is formed on the surface. The terminal fitting 13 includes a seal portion 13c, a terminal portion 13a protruding from the rear end edge of the insulator 2, and a rod-like portion 13b connecting the terminal portion 13a and the seal portion 13c. Note that the outer peripheral surface of the seal portion 13 c is processed into a screw shape or a knurled shape, and the space between the inner surface of the through hole 6 is sealed by the conductive glass seal layer 17.

  A resistor 15 is disposed between the terminal fitting 13 and the center electrode 2 in the through hole 6. Both ends of the resistor 15 are electrically connected to the center electrode 3 and the terminal fitting 13 through the conductive glass seal layers 16 and 17, respectively. The resistor 15 is composed of the resistor composition of the present invention already described in detail. The conductive glass seal layers 16 and 17 are made of glass mixed with metal powder mainly composed of one or more metal components such as Cu, Sn, and Fe. In addition, an appropriate amount of semiconductive inorganic compound powder such as TiO 2 can be blended in the conductive glass seal layer as necessary.

  As shown in FIG. 1, a protruding portion 2 e that protrudes outward in the circumferential direction is formed, for example, in a flange shape in the middle of the insulator 2 in the axial direction. The insulator 2 has a main body 2b in which the side toward the tip of the center electrode 3 (FIG. 1) is the front side, and the rear side of the protrusion 2e is formed with a smaller diameter. On the other hand, on the front side of the protruding portion 2e, a first shaft portion 2g having a smaller diameter and a second shaft portion 2i having a smaller diameter than the first shaft portion 2g are formed in this order. A corrugation 2c is formed at the rear end of the outer peripheral surface of the main body 2b. Further, the outer peripheral surface of the first shaft portion 2g is substantially cylindrical, and the outer peripheral surface of the second shaft portion 2i is substantially conical, with a diameter decreasing toward the tip.

  On the other hand, the axial sectional diameter of the center electrode 3 is set smaller than the axial sectional diameter of the resistor 15. The through-hole 6 of the insulator 2 has a substantially cylindrical first portion 6a through which the center electrode 3 is inserted, and a substantially cylindrical shape having a larger diameter on the rear side (upper side in the drawing) of the first portion 6a. Second portion 6b. As shown in FIG. 1, the terminal fitting 13 and the resistor 15 are accommodated in the second portion 6b, and the center electrode 3 is inserted into the first portion 6a. At the rear end portion of the center electrode 3, an electrode fixing convex portion 3a is formed so as to protrude outward from the outer peripheral surface thereof. The first portion 6a and the second portion 6b of the through hole 6 are connected to each other in the first shaft portion 2g, and the connection position receives the electrode fixing convex portion 3a of the center electrode 3. The convex portion receiving surface 6c is formed in a tapered surface or a rounded surface.

  Further, the outer peripheral surface of the connecting portion 2h between the first shaft portion 2g and the second shaft portion 2i is a stepped surface, and this is a convex portion 1c as a metal shell side engaging portion formed on the inner surface of the metal shell 1. Are engaged with each other via a ring-shaped plate packing 63 to prevent the axial removal. On the other hand, a ring-shaped wire packing 62 that engages with the rear peripheral edge of the flange-shaped protrusion 2e is disposed between the inner surface of the rear opening of the metal shell 1 and the outer surface of the insulator 2, and further On the rear side, a ring-shaped packing 60 is arranged via a filling layer 61 such as talc. Then, the insulator 2 is pushed forward toward the metal shell 1, and in this state, the opening edge of the metal shell 1 is crimped inward toward the packing 60 to form a crimped portion 1d. It is fixed with respect to the insulator 2.

5A and 5B show some examples of the insulator 2. The dimension of each part is illustrated below.
-Total length L1: 30-75 mm.
The length L2 of the first shaft portion 2g: 0 to 30 mm (however, the connection portion 2f with the locking projection 2e is not included, but the connection portion 2h with the second shaft portion 2i is included).
-Length L3 of the second shaft portion 2i: 2 to 27 mm.
-Outer diameter D1 of the main body 2b: 9 to 13 mm.
The outer diameter D2 of the locking projection 2e is 11 to 16 mm.
-Outer diameter D3 of the first shaft portion 2g: 5 to 11 mm.
-The base end outer diameter D4 of the second shaft portion 2i: 3 to 8 mm.
The distal end outer diameter D5 of the second shaft portion 2i (however, when the outer peripheral edge of the distal end surface is rounded or chamfered, the base end position of the rounded portion or chamfered portion in the cross section including the central axis O) The outer diameter is indicated by 2.5 to 7 mm.
-Inner diameter D6 of the 2nd part 6b of the through-hole 6: 2-5 mm.
The inner diameter D7 of the first portion 6a of the through hole 6 is 1 to 3.5 mm.
-Thickness t1 of the first shaft portion 2g: 0.5 to 4.5 mm.
-Base end portion thickness t2 of second shaft portion 2i (value in a direction orthogonal to central axis O): 0.3 to 3.5 mm.
The thickness t3 of the tip end of the second shaft 2i ((value in a direction orthogonal to the center axis O; however, when the outer peripheral edge of the tip face is rounded or chamfered, in the cross section including the center axis O, The thickness at the base end position of the rounded portion or the chamfered portion is indicated): 0.2 to 3 mm.
-Average wall thickness tA (= (t1 + t2) / 2) of the second shaft portion 2i: 0.25 to 3.25 mm.

  5A is, for example, as follows: L1 = about 60 mm, L2 = about 10 mm, L3 = about 14 mm, D1 = about 11 mm, D2 = about 13 mm, D3 = about 7.3 mm, D4 = 5.3 mm, D5 = 4.3 mm, D6 = 3.9 mm, D7 = 2.6 mm, t1 = 3.3 mm, t2 = 1.4 mm, t3 = 0.9 mm, tA = 1. 2 mm.

  In addition, in the insulator 2 shown in FIG. 5B, the first shaft portion 2g and the second shaft portion 2i each have a slightly larger outer diameter than that shown in FIG. 5A. The dimensions of each part are, for example, as follows: L1 = about 60 mm, L2 = about 10 mm, L3 = about 14 mm, D1 = about 11 mm, D2 = about 13 mm, D3 = about 9.2 mm, D4 = 6.9 mm, D5 = 5.1 mm, D6 = 3.9 mm, D7 = 2.7 mm, t1 = 3.3 mm, t2 = 2.1 mm, t3 = 1.2 mm, tA = 1.7 mm.

  Next, as shown in FIGS. 2 and 3, the main body portions 3a and 4a of the center electrode 3 and the ground electrode 4 are made of Ni alloy or the like. A core material 3b made of Cu or Cu alloy is embedded in the main body 3a of the center electrode 3 to promote heat dissipation. On the other hand, the ignition part 31 and the opposing ignition part 32 are mainly composed of a noble metal alloy mainly composed of one or more of Ir, Pt and Rh. As shown in FIG. 3, the main body portion 3a of the center electrode 3 has a distal end with a reduced diameter and a flat distal end surface, on which a disk-shaped chip made of an alloy composition constituting the ignition portion is stacked. In addition, the ignition part 31 is formed by forming a welded part W by laser welding, electron beam welding, resistance welding or the like along the outer edge of the joint surface and fixing it. Further, the opposing ignition part 32 is formed by aligning the tip with the ground electrode 4 at a position corresponding to the ignition part 31, and similarly forming a welded part W along the outer edge of the joint surface to fix it. It is formed. These chips are formed and sintered by, for example, a melting material obtained by mixing and melting each alloy component so as to have a predetermined composition, or an alloy powder or a single metal component powder mixed at a predetermined ratio. It can comprise with the sintered material obtained by these. Note that at least one of the ignition part 31 and the opposing ignition part 32 may be omitted.

  The spark plug 100 is manufactured, for example, by the following method. First, the insulator 2 is manufactured by firing a molded body of a predetermined raw material powder. Then, a glaze slurry is applied to a predetermined surface region of the insulator 2 to form a glaze slurry application layer 2d '(FIG. 6), which is dried.

  Next, an outline of the process of assembling the center electrode 3 and the terminal fitting 13 and forming the resistor 15 and the conductive glass sealing layers 16 and 17 to the insulator 2 on which the glaze slurry coating layer 2d ′ is formed. Is as follows. First, as shown to Fig.6 (a), after inserting the center electrode 3 in the 1st part 6a with respect to the through-hole 6 of the insulator 2, it fills with the conductive glass powder H as shown to (b). . Then, as shown in (c), a pressing rod 28 is inserted into the through-hole 6 and the filled powder H is pre-compressed to form the first conductive glass powder layer 26. Subsequently, the raw material powder of the resistor composition is filled and pre-compressed in the same manner, and further, the conductive glass powder is filled and pre-compressed, and as shown in FIG. When viewed from the electrode 3 side (lower side), the first conductive glass powder layer 26, the resistor composition powder layer 25, and the second conductive glass powder layer 27 are laminated.

  Then, as shown in FIG. 7A, an assembly PA in which the terminal fitting 13 is disposed in the through hole 6 from above is formed. And in this state, it inserts in a furnace and heats to the predetermined temperature of 800-950 degreeC which is more than a glass softening point, and press-fits the terminal metal fitting 13 into the through-hole 6 from the opposite side to the center electrode 3 in the axial direction. Then, the layers 25 to 27 in the laminated state are pressed in the axial direction. As a result, as shown in FIG. 4B, the layers are compressed and sintered to become the conductive glass seal layer 16, the resistor 15, and the conductive glass seal layer 17, respectively (the glass sealing step).

The metal shell 1, the ground electrode 4, and the like are assembled to the assembly PA in which the glass sealing process is completed in this way, and the spark plug 100 shown in FIG. 1 is completed. The spark plug 100 is attached to the engine block at the threaded portion 7 via the gasket 101, and is used as an ignition source for the air-fuel mixture supplied to the combustion chamber.

Hereinafter, the effects of the present invention will be described in more detail with reference to the following examples.
(Example 1)
Fine glass powder (average particle size 80 μm), TiO 2 powder, various ceramic powders other than TiO 2 (average particle size 1 to 4 μm), various metal powders for forming a metal phase (average particle size 20 to 50 μm), non-metallic conductive material powder Carbon black as a mixture and dextrin as an organic binder were blended in predetermined amounts, wet mixed with a ball mill using water as a solvent, and then dried to prepare a preparation material. Next, a predetermined amount of coarse glass powder (average particle size 250 μm) was blended into this to make a raw material base, which was hot press molded at a temperature of 900 ° C. and a pressure of 100 MPa to obtain a resistor composition.

  The material of the glass powder is lithium borosilicate glass obtained by mixing and dissolving 50% by weight of SiO2, 29% by weight of B2O3, 4% by weight of Li2O, and 17% by weight of BaO, and its softening temperature is It was 585 ° C. TiO2 has a particle size distribution with an average particle size of 0.4 μm, a standard deviation of particle size of σ, and a 3σ range centered on the average particle size of 0.05 to 0.5 μm (hereinafter referred to as A). Type) and an average particle size of 4 μm, a standard deviation of particle size as σ, and a 3σ range centering on the average particle size having a particle size distribution of 2 to 8 μm (hereinafter referred to as B type) as appropriate The mixture was used at a ratio of X-ray diffraction revealed that 90% by weight or more of the former A type TiO2 was anatase type, and 90% by weight or more of the latter B type TiO2 was rutile type. .

  About the obtained resistor composition, each content ratio with respect to all the TiO2 of a rutile type TiO2 and an anatase type TiO2 was calculated | required by X-ray diffraction. The results are shown in Table 1, Table 3, and Table 5. Moreover, in each table | surface, the value estimated from the compounding ratio at the time of resistor composition preparation is shown about content of ceramic other than coarse glass, fine glass, TiO2, and TiO2, and a metal phase. The carbon content in the resistor composition was determined by gas analysis. Furthermore, the average particle diameter of the mixed TiO2 powder of the A type and B type was measured using a laser diffraction particle size analyzer.

  And the sample of height 3mm, width 3mm, and length 10mm was cut out from the said resistor composition, and the value of the electrical resistivity of the bulk was measured by the Wheatstone bridge method. Moreover, the resistor composition was cut into a predetermined shape to produce a sample for determination of baking tightening, and the cross section was observed with an optical microscope (magnification 20 times). A considerable amount of pores are observed, and those that absorb water instantly when a small amount of water is dripped are judged to be poorly squeezed (x), and those that hardly have pores observed and do not absorb water are judged to be good squeezed (○). did. The results are shown in Table 2, Table 4, and Table 6 (in addition, each result in Table 2, Table 4, and Table 6 corresponds to the composition of the resistor composition in Table 1, Table 3, and Table 5, respectively). .

  Next, the resistor 15 of the spark plug 100 shown in FIG. 1 was produced by the method shown in FIGS. 6 and 7 using the above resistor compositions. 5 are as follows: L1 = about 60 mm, L2 = about 10 mm, L3 = about 18 mm, D1 = about 10 mm, D2 = about 12 mm, D3 = about 9 mm, D4 = 7 mm, D5 = 5 mm, D6 = 4 mm, D7 = 2.5 mm, t1 = 2.5 mm, t2 = 2.0 mm, t3 = 1.2 mm, tA = 2.25 mm. Furthermore, as the conductive glass powder, a mixture of Cu powder and calcium borosilicate glass (softening temperature 780 ° C.) powder in a weight ratio of 1: 1 was used. In order to form the conductive glass seal layer 16, 0.2 g of the conductive glass powder is used, and in order to form the resistor 15, 0.5 g of the raw material base is used. In order to form the layer 17, 0.3 g of the above conductive glass powder was used.

  The load life characteristics of these spark plugs 100 were measured by the following method. That is, a change in the resistance value was measured after a spark plug was attached to an automobile transistor ignition device and discharged for 100 hours under the conditions of a discharge voltage of 20 kV and a discharge frequency of 3600 times / minute. Judgment conditions were determined as bad (x) when positive resistance value change of 2 kΩ or more occurred, and as good (◯) when not.

  The radio wave noise characteristic is that the electric field strength of the interference wave emitted by the spark plug 100 is measured at a test frequency of 5 to 1000 MHz by a measurement method stipulated in the CISPR (International Radio Interference Special Committee) standard, and the electric field strength is determined by the CISPR standard. Those that were 3 dB or more smaller than the obtained limit value (hereinafter referred to as CISPR limit value) were judged as excellent (◎), those that were less than CISPR limit value as good (◯), and those that exceeded CISPR limit value as bad (x). The temperature characteristics are as follows: γ = (α2−α1) / α1 where the resistance value at 20 ° C. between the terminal fitting 13 and the center electrode 3 is α1, and the resistance value at 150 ° C. (held for 2 hours) is α2. Γ is −0.25 to 0 (excellent), −0.30 to −0.25 is good (◯), and less than −0.30 is defective (×). did. The above results are shown in Table 2, Table 4, and Table 6.

  First, as shown in Tables 1 and 2, in the case of a spark plug in which the content ratio of rutile TiO2 and anatase TiO2 in the resistor composition is substantially constant, the total content of TiO2 is 0.5. Those within the range of ˜20% by weight are found to have good load life characteristics and temperature characteristics. The value of γ is also −0.30 or more.

  Next, as shown in Table 3 and Table 4, in the spark plug in which the average particle diameter of TiO2 in the resistor composition is 0.5 to 20 μm, it is understood that the radio wave noise characteristics and the load life characteristics are good. . In addition, it can be seen that in the spark plug in which the content ratio of the rutile-type phase in the total amount of TiO 2 is 20% by weight or more, good temperature characteristics are obtained. Moreover, as shown in Tables 5 and 6, when the content of carbon in the resistor composition is 0.5 to 5% by weight, both the radio noise characteristics and the load life characteristics are good. I understand.

(Example 2)
Fine glass powder (average particle size 80 μm), MgTiO 3, MgZrO 3, CaTiO 3, SrTiO 3, BaTiO 3 and BaZrO 3 as specific composite oxide (average particle size 0.1 to 25 μm), ceramic powder other than specific composite oxide ZrO2 (average particle size 1 to 4 μm), various metal powders for forming a metal phase (average particle size 20 to 50 μm), carbon black as a nonmetallic conductive material powder, and dextrin as an organic binder are blended in predetermined amounts, Wet mixing was performed with a ball mill using water as a solvent, and then this was dried to prepare a preparation material. For comparison, a preparation material using TiO 2 (anatase type) instead of the specific composite oxide was also produced.

  Next, a predetermined amount of coarse glass powder (average particle size 250 μm) was blended into this to form a raw material base, which was hot press molded at a temperature of 900 ° C. and a pressure of 100 MPa to obtain a resistor composition. The material of the glass powder is the same as in Example 1. About the obtained resistor composition, carbon content was calculated | required by the gas analysis. The results are shown in Table 7. Table 7 shows the contents of coarse glass, fine glass, specific composite oxide, and ceramics other than the specific composite oxide, as values estimated from the blending ratio at the time of preparing the resistor composition. Yes.

  The bulk electrical resistivity of the resistor composition was measured in the same manner as in Example 1. Various spark plugs similar to those in Example 1 except for the composition of the resistor 15 were produced, and similar experiments were performed. Table 8 shows the above results.

  That is, when the total content of the specific composite oxide of the resistor is in the range of 0.5 to 20% by weight, the load life is compared with that using TiO2 instead of the specific composite oxide. It can be seen that both the characteristics and the temperature characteristics are good, and the value of γ is −0.30 or more. Furthermore, it can be seen that the spark plug in which the average particle size of the specific composite oxide in the resistor composition is 0.5 to 20 μm has good radio noise characteristics and load life characteristics.

(Example 3)
Fine glass powder (average particle size 80 μm), metallic Ti powder or Ti 3 O 5 powder (average particle size 0.5 to 200 μm), ZrO 2 (average particle size 1 to 4 μm) as ceramic powder, carbon black as non-metallic conductive material powder A predetermined amount of PVA as an organic binder was blended, wet mixed with a ball mill using water as a solvent, and then dried to prepare a preparation material. For comparison, a preparation material using TiO 2 (anatase type) instead of the specific composite oxide was also produced.

  Next, a predetermined amount of coarse glass powder (average particle size 250 μm) was blended into this to form a raw material base, which was hot press molded at a temperature of 900 ° C. and a pressure of 100 MPa to obtain a resistor composition. The material of the glass powder is the same as in Example 1. About the obtained resistor composition, carbon content was calculated | required by the gas analysis. The results are shown in Table 10. Table 9 shows the contents of coarse glass, fine glass, metal Ti, Ti3O5, and ZrO2 as values estimated from the blending ratio at the time of preparing the resistor composition.

  The bulk electrical resistivity of the resistor composition was measured in the same manner as in Example 1. Various spark plugs similar to those in Example 1 except for the composition of the resistor 15 were produced, and similar experiments were performed. Table 10 shows the above results.

  That is, it can be seen that the compound containing metal Ti or Ti3O5 in the resistor has better load life characteristics and temperature characteristics than those using TiO2 instead. In this case, the content of the metal Ti or Ti3O5 is set to 0.5 to 10% by weight (preferably 3 to 5% by weight), or the particle diameter thereof is set to 5 to 100 μm (preferably 20 to 50 μm). It can be seen that even better results are obtained.

Example 4
Fine glass powder (average particle size 80 μm), TiC or TiN powder (average particle size 0.7-5 μm, the amount of oxygen contained is identified in advance by gas analysis), ZrO 2 as ceramic powder (average particle size 1-4 μm) A predetermined amount of PVA as an organic binder was blended, wet mixed with a ball mill using water as a solvent, and then dried to prepare a preparation material. For comparison, a material using carbon black (average particle size 0.06 μm) instead of TiC or TiN powder was also prepared.

  Next, a predetermined amount of coarse glass powder (average particle size 250 μm) was blended into this to form a raw material base, which was hot press molded at a temperature of 900 ° C. and a pressure of 100 MPa to obtain a resistor composition. The material of the glass powder is lithium borosilicate-barium glass obtained by blending and dissolving 60 parts by weight of SiO2, 25 parts by weight of B2O3, 5 parts by weight of Li2O, and 7 parts by weight of BaO. The temperature was 720 ° C. About the obtained resistor composition, carbon content was calculated | required by the gas analysis. The results are shown in Tables 11 and 13. Moreover, in Table 11 and Table 13, each content of coarse glass, fine glass, TiC or TiN, and ZrO2 is shown by the value estimated from the mixture ratio at the time of resistor composition preparation. The carbon component amount WC1 contained in TiC is estimated from the total analysis amount WC0 of the carbon component (in this example, estimated from the compounding amount of TiC, but the resistor is directly analyzed by ICP analysis or the like to contain the Ti component) The amount of free carbon component WCP (= WC 0 -WC 1) is calculated by subtracting the amount obtained and calculating the amount of the carbon component equivalent to this amount.

  The bulk electrical resistivity of the resistor composition was measured in the same manner as in Example 1. Various spark plugs similar to those in Example 1 except for the composition of the resistor 15 were produced, and the following experiment was performed. The load life characteristics are as follows. First, the initial resistance value R0 of the spark plug is measured, and then this is attached to an automobile transistor ignition device, the temperature of the spark plug is raised to 350 ° C., the discharge voltage is 20 kV, and the discharge frequency is 3600 times / minute. The resistance value after discharging for 300 hours was defined as R, and the resistance value change rate ΔR = {(R−R0) / R} × 100 (%) was evaluated. The radio noise characteristics were evaluated in the same manner as in Example 1. The above results are shown in Tables 12 and 14.

  That is, it can be seen that those using TiC or TiN instead of part of carbon black as the conductive material have good load life characteristics even at high temperatures (350 ° C.). In this case, by setting the content of TiC or TiN to 1 to 10% by weight (preferably 5 to 6% by weight), the initial resistance value is also relatively low, and particularly good results in radio noise prevention performance are obtained. ing. It can also be seen that if the particle size of TiC or TiN is 5 μm or less, or the oxygen content of the starting TiC or TiN powder is set to less than 3% by weight, the load life characteristics can be further improved.

(Example 5)
A predetermined amount of fine glass powder (average particle size of 80 μm), carbon black having various particle sizes and structure lengths, ZrO 2 (average particle size of 1 to 4 μm) as ceramic powder, and polyethylene glycol as an organic binder are mixed, and water Was prepared by wet mixing with a ball mill using as a solvent, and then drying to prepare a preparation material. The average particle size of carbon black was measured using a laser diffraction particle size meter, and the structure length was measured by the method described in the JIS.

  Next, a predetermined amount of coarse glass powder (average particle size 250 μm) was blended into this to form a raw material base, which was hot press molded at a temperature of 900 ° C. and a pressure of 100 MPa to obtain a resistor composition (sample) Numbers 1 to 24). The material of the glass powder is the same as that in Example 1. Table 15 shows the apparent density values measured by the Archimedes method for each of the obtained resistor compositions. Moreover, in Table 15, each content of coarse glass, fine glass, and ZrO2 is shown by the value estimated from the compounding ratio at the time of resistor composition preparation. Next, various spark plugs similar to Example 1 except for the composition of the resistor 15 were produced (n = 20 for each sample number). The initial value of the electric resistance value of each spark plug (the value between the center electrode 3 and the terminal fitting 13 via the resistor 15) is 5 kΩ ± 0.3 kΩ depending on the amount of carbon black. It is adjusted. The following experiment was conducted using these spark plugs.

  First, the electrical resistance value of each spark plug (the value between the center electrode 3 and the terminal fitting 13 via the resistor 15) is measured by the Wheatstone bridge method, and the standard deviation is calculated for each sample number. ◎ (excellent) when 3σ <0.6, ○ (good) when 0.6 ≦ 3σ <1.2, and Δ when 1.2 ≦ 3σ <1.8 (Yes), 3σ ≧ 1.8 was evaluated as x (impossible). As for the load life characteristics, first, the initial resistance value R0 of the spark plug is measured, and then it is attached to an automobile transistor ignition device and discharged at a discharge voltage of 20 kV and a discharge frequency of 3600 times / minute for 250 hours. Evaluation was made by measuring the resistance value change rate ΔR = {(R−R 0) / R} × 100 (%), where R is the resistance value of the resistance value. In addition, the judgment is Δ (excellent) if ΔR is within ± 15%, ○ (good) if it is within ± 25%, Δ (good) if it is within ± 30%, and more than ± 30%. X (impossible). The results are shown in Table 15.

From this experimental result, the following is found.
That is, when carbon black having an average particle diameter of 20 nm to 80 nm and a structure length of 60 ml to 120 ml / 100 g is used, a specified electric resistance value (in this case, 5 ± 0.3 kΩ) is obtained. The amount of carbon black added can be reduced, and the apparent density of the resistor is increased. In addition, there is little variation in resistance value, and good results are obtained in load life characteristics.

The whole front sectional view showing an example of the spark plug of the present invention. The front fragmentary sectional view of the principal part of FIG. Sectional drawing which expands further and shows the vicinity of the ignition part of FIG. The schematic diagram which shows the structure of a resistor. Longitudinal sectional view showing some examples of insulators Explanatory drawing of a glass sealing process. Explanatory drawing following FIG. Explanatory drawing which defines the dimension of the various particles in a resistor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main metal fitting 2 Insulator 3 Center electrode 4 Ground electrode 13 Terminal metal fitting 15 Resistor 16, 17 Conductive glass seal layer

Claims (35)

A terminal fitting is fixed to one end side of the through hole formed in the axial direction of the insulator, and a center electrode is fixed to the other end side, and the terminal fitting is placed in the through hole. A resistor composed of a resistor composition mainly composed of a conductive material, glass particles, and ceramic particles other than glass is disposed between the central electrode and the center electrode,
The resistor composition contains semiconductor ceramic particles as the ceramic particles,
(Α2−α1) where α1 is a value at 20 ° C. and α2 is a value at 150 ° C. of an electrical resistance value measured by energizing the resistor between the terminal fitting and the center electrode. /Α1≧−0.30, a spark plug containing a resistor. In the range of 0.5 to 20% by weight of TiO2 particles in which the average particle diameter of the particle image obtained when the cross-sectional structure is observed as the semiconductive ceramic particles is 0.5 to 20 μm as the semiconductor ceramic particles. The spark plug containing a resistor according to claim 1, wherein the spark plug contains at least part of the TiO2 particles and has a rutile crystal structure. The spark plug with a resistor according to claim 2, wherein 20% by weight or more of the TiO2 particles in the resistor composition has a rutile-type crystal structure. The TiO2 particles in the resistor composition have a content ratio of TiO2 particles belonging to a particle size range of 0.05 to 0.5 [mu] m of 20 to 80% by weight and a content ratio of TiO2 particles belonging to a particle size range of 2 to 8 [mu] m. The spark plug with a resistor according to claim 2 or 3, wherein is 80 to 20 wt%. The resistor composition, as the semiconducting ceramic particles, is at least one of semiconducting metal titanate complex oxide and semiconducting metal zirconate complex oxide (hereinafter collectively referred to as both) The resistor-containing spark plug according to claim 1, wherein the specific composite oxide is contained in the range of 0.5 to 20% by weight. 6. The spark plug with a resistor according to claim 5, wherein the specific composite oxide is at least one of titanate of an alkaline earth metal element and zirconate of an alkaline earth metal. The spark plug containing a resistor according to claim 6, wherein the specific composite oxide is one or more selected from MgTiO3, MgZrO3, CaTiO3, CaZrO3, SrTiO3, SrZrO3, BaTiO3 and BaZrO3. The spark plug containing a resistor according to any one of claims 5 to 7, wherein in the resistor composition, an average particle size of the particles of the specific composite oxide is 0.5 to 20 µm. The resistor composition is:
50 to 90% by volume of block glass particles made of glass particles belonging to a particle size range of 150 to 800 μm,
It contains the conductive material, the ceramic particles, and a bonded glass phase that binds to each other in a state in which the conductive material and the ceramic particles are dispersed to form a space between the block glass particles, and the resistance 10 to 50% by volume of a conductive path forming part for forming a conductive path in the body,
A spark plug containing a resistor according to any one of claims 2 to 8. The resistor-containing spark plug according to any one of claims 2 to 9, wherein a content of the ceramic particles other than the TiO2 particles or the specific composite oxide particles is 2 to 32% by weight. 11. The conductive material according to claim 9, wherein the conductive material contains a metal phase mainly composed of one or more of Al, Mg, Ti, Zr, and Zn, and a non-metallic conductive material. Spark plug with resistor. The said resistor composition contains 10-80 volume% in the volume content ratio which occupies the said TiO2 particle | grains or the said specific composite oxide particle in the said conductive path formation part. Spark plug with resistor. The spark plug containing a resistor according to any one of claims 2 to 12, wherein a content of a carbon component in the resistor composition is 0.5 to 5% by weight. The resistor composition includes titanium suboxide represented by a metal phase mainly composed of Ti as the conductive material (hereinafter referred to as Ti metal phase) and a composition formula TinO2n-1 as the semiconductive ceramic particles. The resistor-containing spark plug according to claim 1, wherein the spark plug contains at least one of particles. The spark plug with a resistor according to claim 14, wherein a total content of the Ti metal phase and / or the titanium suboxide particles in the resistor composition is 0.5 to 10% by weight. The spark plug with a resistor according to claim 14 or 15, wherein an average particle diameter of the Ti metal phase and / or the titanium suboxide particles is 5 µm to 100 µm. The spark plug containing a resistor according to any one of claims 14 to 16, wherein the titanium suboxide particles are mainly composed of at least one of TiO, Ti2O3, and Ti3O5. The resistor composition includes 2 to 60% by weight of glass,
2 to 65% by weight of the ceramic particles;
The spark plug containing a resistor according to any one of claims 14 to 17, comprising 0.1 to 7% by weight of a carbon component. A terminal fitting is fixed to one end side of the through hole formed in the axial direction of the insulator, and a center electrode is fixed to the other end side, and the terminal fitting is placed in the through hole. A resistor composed of a resistor composition mainly composed of a conductive material, glass particles, and ceramic particles other than glass is disposed between the central electrode and the center electrode,
The resistor composition is mainly composed of a resistor composition containing, as the ceramic particles, TiO2 particles having an average particle diameter of 0.5 to 20 μm in a range of 0.5 to 20% by weight,
A spark plug containing a resistor, wherein at least a part of the TiO2 particles in the resistor composition has a rutile crystal structure. A terminal fitting is fixed to one end side of the through hole formed in the axial direction of the insulator, and a center electrode is fixed to the other end side, and the terminal fitting is placed in the through hole. A resistor composed of a resistor composition mainly composed of a conductive material, glass particles, and ceramic particles other than glass is disposed between the central electrode and the center electrode,
The resistor composition is at least one of a semiconducting metal titanate complex oxide and a semiconducting zirconate complex oxide (hereinafter referred to as a specific composite when both are collectively referred to) as the ceramic particles. A spark plug containing a resistor, characterized by containing an oxide in the range of 0.5 to 20% by weight. A terminal fitting is fixed to one end side of the through hole formed in the axial direction of the insulator, and a center electrode is fixed to the other end side, and the terminal fitting is placed in the through hole. A resistor composed of a resistor composition mainly composed of a conductive material, glass particles, and ceramic particles other than glass is disposed between the central electrode and the center electrode,
The resistor composition includes a metal phase mainly composed of Ti as the conductive material (hereinafter referred to as Ti-based metal phase) and titanium suboxide particles represented by a composition formula TinO2n-1 as the ceramic particles. A spark plug containing a resistor, comprising a resistor composition containing at least one of them. The spark plug containing a resistor according to any one of claims 1 to 21, wherein the resistor composition has an electric specific resistance at 20 ° C of 50 to 2000 Ω · cm. A terminal fitting is fixed to one end side of the through hole formed in the axial direction of the insulator, and a center electrode is fixed to the other end side, and the terminal fitting is placed in the through hole. A resistor composed of a resistor composition mainly composed of a conductive material, glass particles, and ceramic particles other than glass is disposed between the central electrode and the center electrode,
The resistor-containing spark plug, wherein the resistor composition contains at least one of TiC particles and TiN particles as a nonmetallic conductive material. The spark plug with a resistor according to claim 23, wherein a total content of the TiC particles and / or the TiN particles in the resistor composition is 1 to 10% by weight. The resistor composition according to claim 23 or 24, wherein in the resistor composition, the TiC particles and / or the TiN particles have an average particle diameter of a particle image obtained by observing a cross-sectional structure of 5 µm or less. Spark plug. The spark plug containing a resistor according to any one of claims 22 to 25, wherein TiC and / or TiN powder having an oxygen content of 3% by weight or less is used as a raw material for the resistor composition. The resistor composition includes 20 to 80% by weight of glass,
The spark plug containing a resistor according to any one of claims 22 to 26, comprising 2 to 60% by weight of the ceramic particles. A terminal fitting is fixed to one end side of the through hole formed in the axial direction of the insulator, and a center electrode is fixed to the other end side, and the terminal fitting is placed in the through hole. And a resistor is disposed between the central electrode and the center electrode,
The resistor composition constituting the resistor is manufactured using a raw material powder mainly composed of glass particles, ceramic particles other than glass, and carbon black particles having an average particle diameter of 20 nm to 80 nm. This is a spark plug with a resistor. As the carbon black powder, those having a DBP (dibutyl phthalate) amount of 60 to 120 ml absorbed by 100 g of carbon black as defined in Japanese Industrial Standard K6221, Method A of 6.1.2 are used. 28. A spark plug containing a resistor according to 28. The raw material powder of the resistor composition is:
20 to 80% by weight of glass powder;
20-50% by weight of ceramic powder;
5-30 wt% carbon black powder;
30. The spark plug containing a resistor according to claim 28 or 29, wherein the spark plug contains 0.05 to 5% by weight of an organic binder. TiO2 particles mainly composed of electrically conductive material glass particles and ceramic particles other than glass, and having an average particle diameter of 0.5 to 20 [mu] m when the cross-sectional structure is observed as the ceramic particles are 0.00. A resistor composition for a spark plug, which is contained in a range of 5 to 20% by weight, and wherein at least a part of the TiO2 particles in the resistor composition has a rutile crystal structure. Mainly composed of conductive material, glass particles, and ceramic particles other than glass, and as the ceramic particles, semiconductive metal titanate metal complex oxide and semiconductive zirconate metal salt complex oxide A resistor composition for a spark plug, comprising at least one (hereinafter referred to as a specific composite oxide when both are collectively referred to) in a range of 0.5 to 20% by weight. A metal phase mainly composed of a conductive material, glass particles, and ceramic particles other than glass and mainly composed of Ti as the conductive material (hereinafter referred to as Ti-based metal phase), and as the ceramic particles A resistor composition for a spark plug, comprising at least one of titanium suboxide particles represented by a composition formula TinO2n-1. A resistor composition for a spark plug, which is mainly composed of a conductive material, glass particles, and ceramic particles other than glass, and contains at least one of TiC particles and TiN particles as a nonmetallic conductive material. Stuff. A terminal fitting is fixed to one end side of the through hole formed in the axial direction of the insulator, and a center electrode is fixed to the other end side, and the terminal fitting is placed in the through hole. A resistor-containing spark plug in which a resistor is disposed between the center electrode and the center electrode,
As a raw material powder for the resistor composition, a resistor powder is used, which is mainly composed of glass particles, ceramic particles other than glass, and carbon black particles having an average particle size of 20 nm to 80 nm. Spark plug manufacturing method.

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